Automatic shoe clearance adjustment apparatus

Abstract

To reduce the number of components of the automatic shoe clearance adjustment apparatus and to improve the ease of assembly of the same, the proximal portion of the driving member is fixed on the strut. The operating portion and the arm of the driving member are integrally formed therewith is placed between the brake shoe and the strut. The operating portion together with the arm of the driving member are moved (rotated) so as to follow the movement of the brake shoe by utilizing the resilient force of the driving member, and the pawl at the end of the arm drives the adjustment teeth of the strut to extend the entire length of the strut.

1 . An automatic shoe clearance adjustment apparatus having: 
 a strut and a driving member,    said strut is comprised of a screw-engaging unit having a nut and a bolt screwed therebetween and a fitting member rotatably fitting with said screw-engaging unit, and extended between one brake shoe and the other brake shoe, and    said driving member engages with adjustment teeth integrated with said screw-engaging unit of the strut,    in which said automatic shoe clearance adjustment apparatus has an automatic shoe clearance adjustment mechanism, automatically extending an entire length of said strut to adjust a shoe-to-drum clearance by driving the adjustment teeth in one direction when strokes of the brake shoes exceed a predetermined value or range, wherein    said driving member is comprised of a proximal portion fixed on said strut at a side being near to said one brake shoe,    an operating portion extending from said proximal portion and resiliently abutting against said one brake shoe between said one brake shoe and said strut in a longitudinal direction of said strut, and    an arm having a pawl extending from said operating portion toward said adjustment teeth to make an engagement therebetween.    
   
   
       2 . The automatic shoe clearance adjustment apparatus according to  claim 1 , wherein 
 said proximal portion of the driving member is fixed to an axial line of said strut, and    said operating portion of the driving member abuts against said one brake shoe on the axial line of said strut between said one brake shoe and said proximal portion.    
   
   
       3 . The automatic shoe clearance adjustment apparatus according to  claim 1 , wherein 
 said proximal portion of the driving member is fixed to said strut by fitting.    
   
   
       4 . The automatic shoe clearance adjustment apparatus according to  claim 2 , wherein 
 said proximal portion of the driving member is fixed to said strut by fitting.    
   
   
       5 . The automatic shoe clearance adjustment apparatus according to  claim 1 , wherein 
 said adjustment teeth is integrally formed with said bolt of the screw-engaging unit, and    said fitting member engages with one of said pair of brake shoes and said nut engages with the other of said pair of brake shoes.    
   
   
       6 . The automatic shoe clearance adjustment apparatus according to  claim 2 , wherein 
 said adjustment teeth is integrally formed with said bolt of the screw-engaging unit, and    said fitting member engages with one of said pair of brake shoes and said nut engages with the other of said pair of brake shoes.    
   
   
       7 . The automatic shoe clearance adjustment apparatus according to  claim 3 , wherein 
 said adjustment teeth is integrally formed with said bolt of the screw-engaging unit, and    said fitting member engages with one of said pair of brake shoes and said nut engages with the other of said pair of brake shoes.    
   
   
       8 . The automatic shoe clearance adjustment apparatus according to  claim 4 , wherein 
 said adjustment teeth is integrally formed with said bolt of the screw-engaging unit, and    said fitting member engages with one of said pair of brake shoes and said nut engages with the other of said pair of brake shoes.    
   
   
       9 . The automatic shoe clearance adjustment apparatus according to  claim 1 , wherein 
 said adjustment teeth is integrally formed with said nut of the screw-engaging unit, and    said fitting member engages with one of said pair of brake shoes and said bolt engages with the other of said pair of brake shoes.    
   
   
       10 . The automatic shoe clearance adjustment apparatus according to  claim 2 , wherein 
 said adjustment teeth is integrally formed with said nut of the screw-engaging unit, and    said fitting member engages with one of said pair of brake shoes and said bolt engages with the other of said pair of brake shoes.    
   
   
       11 . The automatic shoe clearance adjustment apparatus according to  claim 3 , wherein 
 said adjustment teeth is integrally formed with said nut of the screw-engaging unit, and    said fitting member engages with one of said pair of brake shoes and said bolt engages with the other of said pair of brake shoes.    
   
   
       12 . The automatic shoe clearance adjustment apparatus according to  claim 4 , wherein 
 said adjustment teeth is integrally formed with said nut of the screw-engaging unit, and    said fitting member engages with one of said pair of brake shoes and said bolt engages with the other of said pair of brake shoes.    
   
   
       13 . The automatic shoe clearance adjustment apparatus according to  claim 1 , wherein 
 an over adjustment prevention means is provided on said arm of the driving member, said over adjustment prevention means suspends an automatic shoe clearance adjustment operation by disengaging said arm from said adjustment teeth by thermo-deflecting of the arm when a temperature within the brake exceeds a predetermined value or range.    
   
   
       14 . The automatic shoe clearance adjustment apparatus according to  claim 2 , wherein 
 an over adjustment prevention means is provided on said arm of the driving member, said over adjustment prevention means suspends an automatic shoe clearance adjustment operation by disengaging said arm from said adjustment teeth by thermo-deflecting of the arm when a temperature within the brake exceeds a predetermined value or range.    
   
   
       15 . The automatic shoe clearance adjustment apparatus according to  claim 3 , wherein 
 an over adjustment prevention means is provided on said arm of the driving member, said over adjustment prevention means suspends an automatic shoe clearance adjustment operation by disengaging said arm from said adjustment teeth by thermo-deflecting of the arm when a temperature within the brake exceeds a predetermined value or range.    
   
   
       16 . The automatic shoe clearance adjustment apparatus according to  claim 4 , wherein 
 an over adjustment prevention means is provided on said arm of the driving member, said over adjustment prevention means suspends an automatic shoe clearance adjustment operation by disengaging said arm from said adjustment teeth by thermo-deflecting of the arm when a temperature within the brake exceeds a predetermined value or range.    
   
   
       17 . The automatic shoe clearance adjustment apparatus according to  claim 5 , wherein 
 an over adjustment prevention means is provided on said arm of the driving member, said over adjustment prevention means suspends an automatic shoe clearance adjustment operation by disengaging said arm from said adjustment teeth by thermo-deflecting of the arm when a temperature within the brake exceeds a predetermined value or range.